Because of its compact size, light weight, large absorbed energy and stable braking force, a disk brake device is used widely as a brake device for a motorcycle, a car, a pickup truck, or the like (see Japanese Patent Application Laid-Open No. 2003-74604, for example). As the main component of such disk brake device, there is a brake disk. The brake disk rotates integrally with a wheel, transmits, to the wheel, braking force caused by the pressure of the brake pad pressing against the both surfaces of the brake disk, and has a function of radiating frictional heat generated between the brake disk and the brake pad at the time of braking. In terms of the outer peripheral shape of the brake disk, there is a circle brake disk as is usually generally used (see Japanese Patent Application Laid-Open No. 2003-74604, for example) and a brake disk having a surface with recesses and ridges repeated in the radial direction (see Japanese Design Registration No. 1179058, and International Patent Publication WO 04/042247, for example).
Although the brake disk, whose outer peripheral shape is formed to have recesses and ridges repeated in the radial direction, is preferred in terms of its improved heat radiation capability, light-weight body, improved design and the like, the brake disk with such outer peripheral shape has problems that the brake pad wears out significantly and the processing cost for molding the brake disk rises. Particularly, in a case of forming a chamfered surface at a corner portion of an outer peripheral edge of the brake disk out of consideration for safety, design and the like, the processing for the formation needs to be carried out for a long period of time using an expensive processing machine or special processing machine such as an NC machining tool or the like since the outer peripheral shape is formed to have recesses and ridges repeated in the radial direction. Therefore, the processing cost for the formation of a chamfered surface increases significantly. For this reason, the brake disk, whose outer peripheral shape is formed to have recesses and ridges repeated in the radial direction, comprises the characteristics of the improved heat radiation capability, the light weight body, the improved design and the like, but has, on the other hand, a problem that such brake disk lacks practicability due to the poor durability of the braking performance and high production costs.
The present invention is contrived in order to solve the problem described above, and an object thereof is to provide a method of producing a highly practical brake disk capable of maintaining the desired performance and at the same time suppressing increase in production costs even in a case of forming a chamfered surface at a corner portion of an outer peripheral edge of a brake disk whose outer peripheral shape is formed to have recesses and ridges repeated in the radial direction, and to provide such brake disk.